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authorAndrew Morton <akpm@osdl.org>2006-06-29 02:24:26 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-29 10:26:20 -0700
commit81b0c8713385ce1b1b9058e916edcf9561ad76d6 (patch)
tree4c5e8fde3d15503c609d5c5f74911f95fc528f03 /mm/filemap.h
parent0686cd8fbe3e5fb1441ae84b9cbc813f9297b879 (diff)
downloadlinux-sh-81b0c8713385ce1b1b9058e916edcf9561ad76d6.tar.gz
[PATCH] generic_file_buffered_write(): handle zero-length iovec segments
The recent generic_file_write() deadlock fix caused generic_file_buffered_write() to loop inifinitely when presented with a zero-length iovec segment. Fix. Note that this fix deliberately avoids calling ->prepare_write(), ->commit_write() etc with a zero-length write. This is because I don't trust all filesystems to get that right. This is a cautious approach, for 2.6.17.x. For 2.6.18 we should just go ahead and call ->prepare_write() and ->commit_write() with the zero length and fix any broken filesystems. So I'll make that change once this code is stabilised and backported into 2.6.17.x. The reason for preferring to call ->prepare_write() and ->commit_write() with the zero-length segment: a zero-length segment _should_ be sufficiently uncommon that this is the correct way of handling it. We don't want to optimise for poorly-written userspace at the expense of well-written userspace. Cc: "Vladimir V. Saveliev" <vs@namesys.com> Cc: Neil Brown <neilb@suse.de> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Greg KH <greg@kroah.com> Cc: <stable@kernel.org> Cc: walt <wa1ter@myrealbox.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm/filemap.h')
-rw-r--r--mm/filemap.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/filemap.h b/mm/filemap.h
index 536979fb4ba7..3f2a343c6015 100644
--- a/mm/filemap.h
+++ b/mm/filemap.h
@@ -88,7 +88,7 @@ filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
const struct iovec *iov = *iovp;
size_t base = *basep;
- while (bytes) {
+ do {
int copy = min(bytes, iov->iov_len - base);
bytes -= copy;
@@ -97,7 +97,7 @@ filemap_set_next_iovec(const struct iovec **iovp, size_t *basep, size_t bytes)
iov++;
base = 0;
}
- }
+ } while (bytes);
*iovp = iov;
*basep = base;
}